This invention relates generally to apparatus for reproducing an information signal from a rotatable disc-shaped record medium on which the information signal is recorded in the form of digital data, such as a digital audio disc, and more particularly to disc players for a disc having digital data recorded thereon wherein the error correcting ability for errors in reproduced digital data in the reproducing state by fast forwarding operation (the cue reproducing state) or in the reproducing state by fast reversing operation (the review reproducing state) is reduced in comparison with the error correcting ability exhibited in the normal reproducing state so as to reduce erroneous error correction in the cue reproducing state or the review reproducing state.
In a digital audio disc system a rotatable disc-shaped record medium having an information track on which various digital data including audio signal data, synchronous data, address data, data for error correction and so on are recorded is provided as a digital audio disc and such a digital audio disc is applied to a disc player for reproducing an audio signal in accordance with the digital data recorded on the digital audio disc. With such a system a reproduced audio signal of high quality can be obtained easily. However, in reproduction of the audio signal from the digital audio disc by the disc player, in case that errors are caused in reproduced digital data obtained from the information track of the digital audio disc, relatively large click niose components are contained in the reproduced audio signal so as to deteriorate the quality of the latter.
In this connection, generally, digital data recorded on a digital audio disc contain almost unavoidably coding errors caused in the recording process though they appear at low probability and therefore the errors caused due to such coding errors would be contained in reproduced digital data obtained from the digital audio disc. Further, fingerprints and scratches on the surface of the digital audio disc would induce errors of relatively large scale in the reproduced digital data.
Accordingly, in the digital audio disc system a method of error correction using a so-called cross-interleave technique is taken to correct the errors induced in the reproduced digital data obtained from the digital audio disc. In such cross-interleave technique, a first error correcting code for a first arrangement stage and a second error correcting code for a second arrangement stage are provided and an interleave is carried out between the first and second arrangement stages. Further, Reed-Solomon Code is adopted for both the first and second error correcting codes. Such a combination of Reed-Solomon Code and the interleave technique provides a significant advance in error correcting ability for errors in the reproduced digital data. The disc player in the system is provided with such an error correcting circuit arrangement as to perform the error correction for the reproduced digital data, which are obtained from the digital audio disc and contain the first and second error correcting codes added in accordance with the cross-interleave technique, with use of the first error correcting code contained in the reproduced digital data at the first arrangement stage and further with use of the second error correcting code also contained in the reproduced digital data at the second arrangement stage.
However, with the aforementioned error correcting circuit arrangement provided in previously proposed disc players, although appropriate error correction is achieved when the disc player is in the normal reproducing state wherein the reproducing digital data are obtained continuously from the digital audio disc, erroneous error correction would be increased when the disc player is in the cue reproducing state or review reproducing state because the reproduced digital data are obtained intermittently from the digital audio disc in the cue reproducing state or review reproducing state. That is, in the cue reproducing state or review reproducing state, a pickup device which is provided in the disc prayer for reading out the digital data recorded on the digital audio disc is controlled to conduct a track jump operation to traverse hundreds of circles of the information track quickly without reading out the digital data and to trace a portion of one circle of the information track for reading out the digital data recorded thereon, alternately. This results in that the lack of the reproduced digital data is caused whenever the pickup device conducts the track jump operation. Consequently, in case that, in the cue reproducing state or review reproducing state, error correction is performed in the same manner as the error corection in the normal reproducing state, erroneous error correction is caused due to such lack of the reproduced digital data at relatively high propability and, as a result of this, click noise components are contained in a reproduced audio signal. Although the reproduced audio signal obtained in the cue reproducing state or review reproducing state is not required to have such high quality as required to the reproducing audio signal obtained in the normal reproducing state, the click noise component in the reproducing audio signal obtained in the cue reproducing state or review reproducing state also produces a harsh click sound and therefore is desired to be eliminated.
To avoid such erroneous error correction as to cause the click noise components in the reproduced audio signal, it is considered to control the error correcting circuit arrangement not to perform any error correction in the cue reproducing state and review reproducing state. However, such a proposal is not desirable because even obvious errors contained in the reproduced digital data are not corrected and relatively large click noise components are induced in the reproduced audio signal thereby.